The present invention relates generally to lighting systems and, more particularly, to a line-of-light illuminating device employing an optical lightpipe for transmitting light by internal reflection and an integral optical lens located at an emission portion of the lightpipe for focusing the reflected light into a collimated line-of-light beam.
It is well known in the field of fiber optics that optical fibers are capable of effectively and efficiently conducting light from a single source along nonlinear paths to various locations remote from the light source without encountering substantial transmission losses. Because of this capability, there is increasing interest in the application of optical fibers to uses where space is restricted. One such use is the overall illumination needs of vehicles where space is scarce due to aerodynamic and styling considerations.
One general approach to the application of optical fibers to vehicular illumination needs is proposed in U.S. Pat. No. 4,811,172 to Davenport et al., U.S. Pat. No. 4,868,718 to Davenport et al., U.S. Pat. No. 4,949,227 to Finch et al., and U.S. Pat. No. 4,958,263 to Davenport et al., all assigned to General Electric Company. These patents disclose various lighting systems that basically employ a plurality of optical fibers having their respective input ends coupled to a high intensity common light source and their respective output ends individually coupled to respective ones of a plurality of paired apertures and optical lenses. Thus, the operative principle underlying this approach is to use one lens and one aperture per optical fiber.
Another approach is shown in my copending application Ser. No. 810,840, wherein there is disclosed a fiberoptic line-of-light illuminating device having a fiberoptic cable providing a plurality of optical fiber bundles, a housing including a block which encapsulates output ends of the optical fibers in splayed-out fashion to form a thin elongated line, and a single optical lens such as a cylindrical lens. The approach shown in my copending application has a number of advantages over the systems discussed above in terms of being substantially miniaturized, easier to assemble, easier to align and less likely to become unaligned than the one-lens-per-optic fiber system. Still, encapsulating a splay of optical fibers presents some manufacturing challenges. It would, therefore, be desirable to form a line-of-light illuminating device from a single lightpipe and optical lens.
Of course lightpipes as such are known. See, for example, Yamashita U.S. Pat. No. 4,733,332 which shows a light transmitting rod illuminated at one end, O'Brien U.S. Pat. No. 2,825,260 which shows a triangular lightpipe amongst other shapes, and Mori U.S. Pat. No. 4,678,279 which shows a modified cylindrical light conducting member. However, the lightpipes shown in these prior patents are generally not capable of being used to provide a line-of-light beam nor are they useful in meeting the overall illumination requirements of vehicles. Thus, there is a need for a line-of-light illuminating device that will satisfy the overall illumination requirements of vehicles while avoiding the aforementioned major shortcomings.